6.49 bfd with /31 addressing

Hi

I have some older ros boxes running 6.49.13, I have a new peering connection, the vendor has sent me a /31 to use.
So I have BGP up and working, but when I attempt to attach BFD to it
its not working, /routing bfd neightber show

4 unspecified xx.xxx.xxx.xxx bgp yes down

strangely as a multihop. when i sniff, I can see packets being set to me, but none being sent to the vendor.

is this just a function of 6.49.
A google suggested bfd was going to be fixed in 7.18.x do i need to upgrade ?

/31 is not supported natively by 6.49 I think /31 started on v7.17 if I were you make a lab and test